This invention relates generally to traction weights for vehicles, and particularly to a system of interlocking plates which may be arranged in various arrays corresponding to the dimensions of different vehicle cargo compartments.
The benefits of increased traction and maneuverability in vehicles which are weighted on the drive wheels are well recognized. Both passenger vehicles and pickup trucks are aided in snow or winter conditions and over rough terrain by placing greater weight on the pair of wheels that provide drive power, or in the case of four wheel drive vehicles on all the wheels.
Recently, the introduction of front wheel drive in many front engine vehicles has provided this same result. In rear wheel drive cars and trucks, however, it is generally necessary to add additional weight in the rear cargo compartment above the rear axle.
People have used a number of different methods to weight their vehicles. One common step is to place bags of sand, salt, or gravel in the trunk or a car or cargo bed of a truck. The salt and sand can also be useful in freeing a vehicle which becomes stuck in the snow or on ice. Unfortunately, the bags may be easily ripped or punctured by many sharp edged items frequently carried in the vehicle cargo compartment, or will become saturated and deteriorate if carried in an open cargo bed.
In place of bags of sand, other people have used bricks or concrete blocks. While being more durable and easy to handle, such bricks or blocks are generally less dense than their bagged counterparts, and will generally shift around in the cargo compartment risking damage to the vehicle or other cargo.
There have been several attempts to design improved systems for adding traction weights to vehicle cargo compartments, predominantly for pickup or similar trucks having cargo beds.
U.S. Pat. No. 3,727,971 discloses a system of utility receptacle units which fit along the sidewalls of a truck's cargo bed, with a recessed region to accommodate the wheel well. These utility compartments may be filled with gravel to increase traction weight, and present less of a risk of puncture or spilling than do bags of similar substances.
U.S. Pat. No. 4,190,281 discloses a system of ballast containers which lock into place along the sidewalls of a truck bed, and may be filled with sand or a similar substance. These ballast containers are designed to fit between the wheel well and the vertical framing and cab wall, and are shaped to lock into place against a sidewall having a particular predetermined configuration.
While being improvements over the concept of using bags of sand or gravel, each of these systems has several common drawbacks. First, each utilizes some of the area of the truck bed which might otherwise be used for storing or transporting cargo. Second, each must be designed and sized to fit a particular type of cargo compartment, depending upon the shape of the sidewalls, placement and dimensions of the wheel wells, and the type of flooring used in the cargo bed. Third, once filled, these weights cannot be easily removed or repositioned without emptying the contents because of the great weight involved Finally, these weight systems would be impractical to use in the cargo compartment of a vehicle other than a pickup truck, such as the trunk of a passenger vehicle.
U.S. Pat. Nos. 3,944,252 and 4,094,534 disclose weight systems mountable on the exterior of a cargo compartment, particularly for the forward end of a tractor or other agricultural vehicle. The weights generally comprise cast metal plates which are removably mounted in a layered configuration on a bracket assembly.
While such a detachable weight system is necessary for the steerable front wheels of tractors and other equipment where a cargo compartment is not available, such systems would be neither practical nor workable in other types of vehicles. First, in most instances it is more important to place additional weight for traction over the drive wheels, and in trucks and passenger vehicles the engine provides sufficient weight over the steerable wheels. Second, it is not desirable to mount such weight systems outside the cargo compartment of either trucks or passenger vehicles. Besides being unattractive, such a mounting configuration greatly hampers the maneuverability of the vehicle by adding additional length or width where it is not within easy view of the driver, and similarly presents a danger to other vehicles. Finally, most trucks and passenger vehicles do not have the exposed frame members necessary to mount such weight systems in the rear of the vehicles where they would be most beneficial.
U.S. Pat. No. 4,482,169 discloses a traction rack for a rear wheel driven truck which is placed on the bed of the truck extending between the wheel wells, the rack holding a series of weights in position over the real axle.
While such a rack system would permit a slightly greater degree of flexibility in accommodating different sized truck beds and wheel well placements, it has several deficiencies. First, such a weight system is only practical to use with a truck cargo bed, and not in a passenger vehicle. Second, while permitting the weight to be focused above the rear axle, such a rack limits the total amount of weight that can be added to a vehicle to a predetermined total number of smaller weights. Third, the rack and weights together occupy the most valuable cargo storage area in the truck bed, directly between the wheel wells where the width of the truck bed is at a minimum. Fourth, because the rack and weights do not extend the full length of the truck bed, they present a hump extending across the width of the truck bed which interferes with placing larger items such as 4'.times.8', panels flat within the truck bed. Finally, the system as disclosed makes the individual weights difficult to remove from the vehicle, either to adjust the weight or provide more cargo space when needed.